1. Field of the Invention
The present invention generally relates to surgical instruments and, in particular, relates to surgical anchors which are configured for securely anchoring within skeletal members, such as vertebrae, for instance.
2. Description of Related Art
Skeletal structures are formed of bones and adjoining structures which include cartilage, for instance. For various reasons, these skeletal structures may require artificial support or stabilization. For example, the human spine is composed of a column of thirty-three bones, called vertebrae, and their adjoining structures. The twenty-four vertebrae nearest the head are separate bones capable of individual movement and generally are connected by anterior and posterior longitudinal ligaments and by discs of fibrocartilage, called intervertbral discs, positioned between opposing faces of adjacent vertebrae. Each of these vertebrae include a vertebral body and a dorsal-arch that enclose an opening, called the vertebral foramen, through which the spinal cord and spinal nerves pass. The remaining nine vertebrae are fused to form the sacrum and the coccyx and are incapable of individual movement.
It is well known in the prior art to utilize pedicle screws for posterior lumbar stabilization procedures. These procedures typically include inserting a pedicle screw posteriorly into the pedicle or pillar of the lumbar spine, and then connecting the screw to either plates or rods for stabilization of the lumbar spine for fractures, tumors and various degenerative conditions. A bone graft also can be added to help solidify the stabilization. When this procedure is used on osteoporotic patients, however, pedicle screw fixation is sometimes difficult to achieve because the threads of the pedicle screw are unable to properly secure within the material of the pillar.
Similar results also may be observed when attempting to secure surgical anchors within the material of other skeletal members.
Therefore, there exists a need for improved surgical anchors which address these and other shortcomings of the prior art.
Briefly stated, the present invention generally relates to improved surgical anchors which are configured for securely anchoring within skeletal members. In a preferred embodiment, the anchor may be configured as a pedicle anchor which is adapted to be anchored within a vertebrae of a spine, for instance. Preferably, each anchor incorporates a passage, such as a longitudinal bore, for instance, for receiving a medical adhesive or boding cement (i.e., methomathactuloid, cranial plast, etc.) therein. The passage communicates with one or more fenestrations or holes, preferably formed at the distal end of the anchor, that allow the bonding cement to pass from and disperse about the anchor. Since at least some of the bonding cement received in the passage passes from the anchor and, preferably, into the material of the skeletal member, i.e., a vertebral body, a firm fixation or anchoring of the anchor within the vertebral body is facilitated. Due to the dispersion of bonding cement into the material of the vertebral body, and an associated increase in the strength of the vertebral body, such an anchoring of the anchor may be facilitated even though the vertebral body is osteoporotic.
In accordance with an aspect of the present invention, some embodiments may incorporate the use of bonding cement which produces an exothermic reaction during curing. In these embodiments, the hole(s) preferably are arranged along a distal one-third of the elongated body, thereby reducing the tendency of the heat produced during curing of the cement from damaging surrounding nerves and/or tissues.
In accordance with another aspect of the present invention, some embodiments of the surgical anchor may incorporate a plug member which is adapted to cooperate with the proximal end of the elongated body for securing the position of the proximal end within a skeletal member.
In accordance with another aspect of the present invention, a system for lumbar spine stabilization is provided. In a preferred embodiment, the system incorporates a plurality of pedicle anchors, with each of the pedicle anchors being configured to engage and anchor within a pedicle of a lumbar spine. Preferably, each of the pedicle anchors incorporate a proximal end, a distal end, a passage, and at least one hole, with the passage extending at least partially through the pedicle anchor from the proximal end, and the hole(s) extending at least partially through the pedicle anchor and communicating with the passage. A supply of bonding cement also is provided, with each of the pedicle anchors being further configured so that bonding cement is receivable in the passage at the proximal end, deliverable through the passage, through the hole(s) and into the pedicle in which the pedicle anchor is engaged.
In accordance with another aspect of the present invention, a method for anchoring a surgical anchor in a skeletal member is provided. Preferably, the method includes the steps of: (1) providing a surgical anchor having a proximal end, a distal end, a passage, and at least one hole, with the passage extending at least partially through the anchor from the proximal end, and the hole(s) extending at least partially through the anchor and communicating with the passage; (2) inserting the anchor at least partially into the skeletal member so that the hole(s) are at least partially disposed within the skeletal member; and, (3) delivering bonding cement into the passage so that at least a portion of the bonding cement is delivered from the passage, through the hole(s), and into the skeletal member.
Other features and advantages of the present invention will become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional features and advantages be included herein within the scope of the present invention, as defined by the claims.